Seal and terminal structure for electric discharge lamp



Jan. 31, 1956 E. B. NOEL 2,733,375

SEAL AND TERMINAL STRUCTURE FOR ELECTRIC DISCHARGE LAMP Filed Aug. 21, 1952 inventor:

Edward [3 Noel.

by Ana- His Atbo ney electric discharge quality of such lamps.

United States Patent 2,733,375 SEAL AND TERMINAL STRUCTURE FOR ELECTRIC DISCHARGE LAMP Edward B. Noel, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application August 21, 1952, Serial No. 305,646 2 Claims. (Cl. 313-217} My invention relates to gaseous electric discharge lamps generally, and more structures therefor.

Inthe manufacture of certain types of tubular gaseous lamps,.such as the flashtubes" employed for flash photography, it has been customary to employ an electrode seal and terminal, or mount, structure at each end of the tubular envelope comprising lead-in wire carrying an electrode and having fusion-sealed thereto a glass flare which is, in turn, fusion-sealed to the end of the envelope. The construction of the glass flares and the sealing of the mounts into the envelope involves considerable expense. Likewise, considerable labor and manual work is involved in tubulating the envelopes, i. e., atfixing thereto a glass exhaust tube through which the envelope is subsequently evacuated and then filled with an ionizable discharge-supporting gas or vapor or mixture of gas and vapor.

It is an object of my invention to provide an improved seal and terminal construction which will provide for increased speed of production, lower cost and improved These objectives are attained, in accordance with my invention, by employing an improved seal and terminal construction utilizing metal cap or disc type seals and metal exhaust tubes. Further features and advantages of my invention will appear from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

The drawing is a perspective view of an electric discharge lamp having a seal and terminal structure embodying the invention.

Referring to the drawing, the lamp or tube comprises a tubular glass envelope 1 herein illustrated as being U- shaped. The ends of the tube are closed and hermetically sealed by small metal caps or discs 2 and 3 having their inner surfaces butt-sealed directly to the ends of the envelope 1 by fusion. The discs 2 and 3 are composed of a metal or alloy which wets glass and has a coefiicient of expansion approximately the same as that of the glass of envelope 1. I prefer to employ for the envelope 1 a hard glass of the borosilicate type, and for the discs 2 and 3 a suitable alloy of iron, nickel and cobalt, such glasses and alloys being in themselves well known in the metal-glass sealing art. Although the caps 2 and 3 may be in the form of fiat discs, for the purpose of providing during assembly, a self-centering action of the envelope ends in the discs, I prefer to make the discs cup-shaped or dished with a radius at the bottom and with sloping sides as shown in the drawing.

Each of the discs 2 and 3 is provided with a central aperture 4 through which extends a terminal conductor 5 and 6, respectively. The apertures 4 around said conductors 5 and 6 are hermetically sealed, preferably by a quantity 7 of suitable brazing metal such as copper. The conductor 5 is composed of a solid wire of nickel, for

example, which carries, on its inner end, a cathode 8 of suitable form and herein illustrated as comprising a doubled-over metal screen member 9 Welded to conductor 5 and enclosing a rod-shaped body 10 of activating and gettering material w 'ch' may consist of barium and aluminum compounds.

The conductor 6, on the other hand, is in the form of a hollow tube, for example a length of seamless tubing of particularly to seal and terminal steel or nickel. While the inner end of the tubular conductor 6 may serve directlyas the anode, I prefer to employ a separate refractory metal member in the form of a suitable metal like tungsten which is scoured around the inner end of the conductor 6. The coil 11 is preferably of such diameter as to snugly engage and grip the conductor 6, thereby avoiding any necessity or likelihood of crimping and closing oh. the tubular conductor 6 during the assembly thereof. The opening through the interior of the conductor is thereby preserved for its function as an exhaust tube during fabrication of the lamp.

conductors 5 and 6. The discs 2 and 3 are then heated, either by gas flames or by induced high frequency currents, and fused to respective ends of the envelope 1. The envelope is then exhausted through the tubular conductor 6 (which is originally of greater length than shown in the drawing) and filled with a suitable ionizable gas such as xenon, after which the said tubular conductor is pinched closed at 12, severed and dipped in solder to hermetically seal it. The conductors 5 and 6 may then be provided with flexible leads 13 and 14 for connection to a suitable source of electrical power supply.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A gaseous electric discharge lamp comprising an elongated tubular glass envelope containing an ionizable gaseous atmosphere, a terminal structure closing and sealing each end of said envelope and comprising a disc of metal having a coeflicient of expansion closely approximating that of the glass envelope, each of said discs having a surface portion thereof fusion-sealed directly to the asin each disc and being hermetically sealed thereto around the aperture by metallic brazing material, one of said conductors being hollow in order to serve as an exhaust tube and having its walls hermetically closed exteriorly of the envelope, the inner end of said hollow tube conductor within the envelope forming an integral part of a metal anode member, and the inner end of the other terminal conductor carrying a metallic cathode member.

2. A gaseous electric discharge lamp comprising an elongated tubular glass envelope containing an ionizablc gaseous atmosphere, :1 terminal structure closing and sealing each end of said envelope and comprising a shallow dished disc of metal having a coefiicient of expansion closely approximating that of the glass envelope, each of said discs enclosing and having its inner surface fusionsealed directly to the associated end of the envelope, a

metal terminal conductor extending into said envelope' References Cited in the file of this patent UNITED STATES PATENTS 2,222,093. Swanson Nov. 19, 1940 2,415,867 Cartun Feb. 18, 1947 2,441,224 Hector May 11, 1948 

1. A GASEOUS ELECTRIC DISCHARGE LAMP COMPRISING AN ELONGATED TUBULAR GLASS ENVELOPE CONTAINING AN IONIZABLE GASEOUS ATMOSPHERE, A TERMINAL STRUCTURE CLOSING AND SEALING EACH END OF SAID ENVELOPE AND COMPRISING A DISC OF METAL HAVING A COEFFICIENT OF EXPANSION CLOSELY APPROXIMATING THAT OF THE GLASS ENVELOPE, EACH OF SAID DICS HAVING A SURFACE PORTION THEREOF FUSION-SEALED DIRECTLY TO THE ASSOCIATED END OF THE ENVELOPE, A METAL TERMINAL CONDUCTOR EXTENDING INTO SAID ENVELOPE THROUGH A CENTRAL APERTURE IN EACH DISC AND BEING HERMETICALLY SEALED THERETO AROUND THE APERTURE BY METALLIC BRAZING MATERIAL, ONE OF SAID CONDUCTORS BEING HOLLOW IN ORDER TO SERVE AS AN EXHAUST TUBE AND HAVING ITS WALLS HERMETICALLY CLOSED EXTERIORLY OF THE ENVELOPE, THE INNER END OF SAID HOLLOW TUBE CONDUCTOR WITHIN THE ENVELOPE FORMING AN INTEGRAL PART OF A METAL ANODE MEMBER, AND THE INNER END OF THE OTHER TERMINAL CONDUCTOR CARRYING A METALLIC CATHODE MEMBER. 